1. Field of the Invention
The present invention relates to ceramic throwaway tips and to a process for producing the same and provides disposable cutting tools comprising silicon nitride as a substratum having high flexural strength and excellent abrasion and shock resistance.
2. Description of the Prior Art
Sinters obtained by molding a finely divided powder of silicon nitride (Si.sub.3 N.sub.4) containing a small amount of additives by hot-pressing are expected to be useful as high temperature materials because of their excellent heat resistance as described in U.S. Pat. Nos. 4,119,690 and 4,131,459. Further, these sinters have potential as cutting tools because of their excellent mechanical strength under high temperatures. However, they are not abrasion resistant. The edge of the tool easily undergoes brittle fracture and also its cutting force is high because the cutting edge dulls during the cutting process. As a result of these problems they have not been practical.